Within the general field of genetic engineering, it has become demonstrated in recent years that it is possible to insert foreign genetic constructions into the inheritable genetic material of higher plants. Through proper manipulation of the genetic construction which is inserted into the plant, it is possible to cause the expression in the cells of plants of heterologous proteins, which then may confer upon the plant new traits which the plant species does not natively possess. Most of the activity in plant genetic engineering to date has focused on improvements to the agronomic or agricultural value of the plants, such as inserting traits for insect resistance, herbicide resistance or traits which might alter one or more of the growing characteristics of the plant. As the genetic engineering of plants becomes more refined, it also now becomes possible to engineer specific plants so that the products produced by the plant have novel and desirable characteristics. The concept described here is directed toward such a novel industrial application for a product produced by cotton or other fiber producing plant.
Cotton was one of the first economically important field crops which was genetically engineered. U.S. Pat. No. 5,004,863 describes what is believed to be the first successful genetic engineering of cotton plants and lines. The transformation technique described in that patent was based on the use of an Agrobacterium, a plant pathogenic bacteria which has an inherent capability to transfer some of its genetic material into plant cells. The same research was reported by Umbeck et al., Bio/Technology, 5:263-266 (1987). Another, newer technique for introducing genes into plants has proven to have wide applicability, due to its ability to transfer genes into plant cells independent of a biological vector such as Agrobacterium. This method is based on the acceleration of small carrier particles carrying genes coated on them into susceptible plant tissues. U.S. Pat. No. 5,015,580 describes an apparatus and method for transforming soybean plants which makes use of an accelerated particle genetic transformation technique.
There are many applications in industry, research, and laboratories where it is desired that a protein be immobilized onto a solid matrix. See, for example, Cowan, D. A., in Biotechnology/The Science and Business. V. Moses and R. E. Cape Eds. 1991, pp. 311-340. Often it is desired to immobilize an enzyme to a solid matrix in such a fashion that its catalytic ability is not affected. One example of such an immobilized enzyme of industrial use is glucose isomerase, which is widely used for the production of fructose syrups in the food industry. The immobilization of enzymes offers several advantages over similar systems in which the enzyme is not immobilized. Systems based on enzyme immobilization offer better protection against denaturing or degradation of the enzyme, typically offer better yields, and are more amenable to efficient reactor technology design, due to the flow-through nature of the reaction. In the past, if an enzyme was immobilized, it was typically fixed or bonded on a solid substrate or matrix. Some of the commonly used enzyme substrates include cellulose, cellulose acetate, silica gel, stainless steel coated with titanium dioxide, polyacrylamide, porous glass, metal oxides, and agarose.
In general, there have been two approaches to the immobilization of useful proteins, a physical approach and a chemical approach. In the physical mode of immobilization, the enzyme or protein is absorbed or entrapped in a matrix. In the chemical mode of immobilization, a variety of chemical processes are utilized to form covalent attachment, or strong cross-linking, between the enzyme and the matrix to which it is attached. The physical method of immobilization, in which the protein is entrapped or absorbed, have a weakness in that it may be susceptible to leakage. On the other hand, chemical immobilization is often relatively laborious, and some of the chemical agents used for the immobilization, notably thiophosgene, are extremely toxic. No system of biological immobilization of useful proteins for industrial procedures has heretofore been reported.
Another disadvantage of currently available techniques for producing immobilized proteins is that the protein must be produced separately and thus somehow entrapped or linked to the substrate. These and other relevant topics on enzyme immobilization and industrial enzymology are reviewed in Godfrey, T. and Reichet, J. Eds. 1983; Handbook of Enzyme Biotechnology, Wiseman, A. Ed. 1985. No system presently existing is capable of producing both a matrix and the immobilized protein in a single production process.